Up until now, as an example of a library device, there has been known a deep-cell type library device (for example, refer to Patent Document 1). This deep-cell type library device includes a recording medium storage unit, a drive device, and an accessor mechanism. The recording medium storage unit stores a plurality of recording media (for example, data cartridges such as tapes and disks) in a manner of arranging them in the depth direction from the front side to the rear side. The drive device reads information recorded on the recording medium and writes information in the recording medium. The accessor mechanism takes a recording medium from the recording medium storage unit to the drive device, and takes a recording medium from the drive device to the recording medium storage unit. Moreover, the accessor mechanism pulls a recording medium from the drive device, and inserts a recording medium into the drive device.